Kia Optima Hybrid: Cooling System / Troubleshooting

Kia Optima Hybrid (TF HEV) 2016-2020 Service Manual / Engine Mechanical System / Cooling System / Troubleshooting

Engine Overheat Troubleshooting

Inspection

Remedy

Visual inspection

Inspect for shortage of coolant in reservoir tank .

Reinspect after replenishing coolant.

Inspect for coolant pollution after removing radiator cap.

Be careful when removing radiator cap from overheated vehicle.

Reinspect after replacing coolant.

Inspect for leakage and loose coolant hoses (radiator hose, heater hose, oil cooler hose, etc.).

Reinspect for leakage after reinstalling hoses and clamps.

Inspect for leakage on water inlet fitting mounting part.

Reinspect for leakage after replacing O-ring.

Reinspect for leakage after tightening to the specified torque.

Inspect drive belt (for normal operation of water pump).

Adjust drive belt tension or replace.

Inspect for leakage on water pump gasket mounting part.

Reinspect for leakage after replacing gasket.

Reinspect for leakage after tightening to the specified torque.

Inspect for loose coolant temperature sensor, cooling fan connector and pin.

Reinstall loose connector.

Replace relevant part if connector pin is damaged.

Inspect operation status of cooling fan.
- Check operation status by switching ON/OFF the heater control A/C.

Will not operate in cold ambient temperature.

Check mounting status of ground cable.

Diagnostic device

Inspect self-diagnostic code using KDS/GDS.

Check coolant temperature sensor, wiring, connector, etc.

Unit inspection

Inspect water pump impeller.

Replace water pump.

Inspect for foreign materials and status of thermostat valve.

Inspect unit after removing foreign materials.

Inspect for stuck thermostat valve.
- Immerse thermostat in water heated to over 95°C (203°F), then heat for at least 3 minutes to check valve lift.

•	Do not use water below 95°C (203°F).

•	Do not directly heat unit as this will damage thermostat.

Check valve lift.
- Replace thermostat if valve lift is below specification or valve is stuck.

Coolant Repair procedures

Refilling And Bleeding Never remove the radiator cap when the engine is hot. Serious scalding could be caused by hot fluid under high pressure escaping from the radiator. When ...

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